Tim Dodd – You didn't read about it at the time because no announcement was made by Freeport-McMoRan, the US company that controls the Freeport copper and gold mine in the Indonesian province of Papua.

But in the early hours of May 25 the company's local headquarters near the mine site, in the company town of Kuala Kencana, was attacked by an armed group of Papuans.

They assaulted one of the guards, started a fire in a security post, broke a door and a window in one of the two buildings, and slashed tires on two parked vehicles.

They apparently wanted to set fire to the buildings – or at least to give the impression that they intended to – because they spread kerosene around, although no major fire eventuated.

Indonesian security forces arrived but nobody was caught. Yesterday, a spokesman for Freeport Indonesia confirmed the incident but could not say whether any suspects had since been arrested.

The May attack on the company offices is nothing compared with last Saturday's assault on a school party travelling on a road in the mine area which killed two Americans and one Indonesian.

But it is part of a pattern of incidents over the years that have the hallmarks of stand-over tactics by the Indonesian military to extract more money and resources from Freeport in exchange for their role in providing "security".

After major riots against Freeport occurred in the area in 1996 the company agreed to build the army a new base, which sources say cost it $US37 million.

It is also said locally, and this is unconfirmed, that new demands for more money followed the May attack on the company offices. And just because the attackers were Papuan does not mean that the army was not behind it. There are more than enough poor, shiftless Papuan males attracted to the Freeport mine by the prospect of money and a job to be suborned by army intelligence.

It is true that not every security incident in the area can be blamed on the security forces. The Freeport mine, in its 30-year-history, has become the honey pot of Papua. In that time the population of the area has risen from about 1,000 traditional tribespeople to more than 100,000 fortune seekers. The main centre of Timika is a frontier town with all the problems created by large numbers of ambitious, and often disappointed, immigrants.

Social and health problems abound, including unemployment and a growing incidence of AIDS. People disappointed at missing out on company handouts have sometimes vented their anger with attacks on Freeport property.

The social divisions were underlined by Freeport's decision to build, during the 1990s, its new company town of Kuala Kencana in virgin jungle about 20km from Timika. This project, lauded by former president Soeharto as a model for the new Indonesian city, is a bizarre creation - an American real estate development mysteriously teleported to the wrong time and place. The golf course alone, with fairways carved through the jungle, is said to have cost Freeport at least $US20 million.

But discontented locals with disappointed hopes have never murdered foreigners. Nor do they have access to the automatic weapons used in the fatal attack.

Security consultants who work for resource companies in Indonesia are reporting that Indonesian police at Timika suspect that a local separatist leader, Titus Morib, may be responsible for the killings.

It is possible that this is correct. He is alienated from the mainstream Free Papua Movement (OPM), most of whose leaders have recently renounced use of violence in favour of a peaceful, politically based independence movement.

Morib belongs to a splinter group which calls itself the People's Papuan Alliance, and possibly he has a motive to undermine the move to peaceful tactics. But over the years a number of so-called independence leaders in Papua have not been what they seemed – many have worked for the army. "The military in the past has used OPM elements as proxies," says Brigham M. Golden, a Columbia University Ph.D candidate who has spent years studying the scene and sits on the US Council for Foreign Relations task force on Papua.

It is more than possible that Morib, or whoever else carried out the killings, was working for the army. Certainly the assault on the teachers does nothing to advance the cause of the separatist movement.

It is potentially extremely damaging to the move by the main independence group, the Papuan Presidium Council, to commit the rebel guerillas to peaceful resistance.

Says Golden: "Nobody has as much to gain as the military does from instability in this region."

The signs are already there that Jakarta is preparing to use the killings as the pretext for a new clampdown on the independence movement. Yesterday, in a statement, the Indonesian Foreign Ministry blamed an "armed separatist group" for the attack.

Unfortunately, we will probably never be sure who was responsible. But on any rational analysis it is a major setback for Papua's independence movement.